I configure those in hadoop-env.sh so I'm not sure about your configuration.
You can check with things like jconsole, or if you're coding it anyways it's the third memory call in runtime, i.e. totalMemory. On 3/25/13, nagarjuna kanamarlapudi <nagarjuna.kanamarlap...@gmail.com> wrote: > Hi Ted, > > As far as i can recollect, I onl configured these parameters > > <property> > <name>mapred.child.java.opts</name> > <value>-Xmx2048m</value> > <description>this number is the number of megabytes of memory that > each mapper and each reducers will have available to use. If jobs start > running out of heap space, this may need to be increased.</description> > </property> > > <property> > <name>mapred.child.ulimit</name> > <value>3145728</value> > <description>this number is the number of kilobytes of memory that > each mapper and each reducer will have available to use. If jobs start > running out of heap space, this may need to be increased.</description> > </property> > > > > On Mon, Mar 25, 2013 at 6:57 AM, Ted <r6squee...@gmail.com> wrote: > >> did you set the min heap size == your max head size? if you didn't, >> free memory only shows you the difference between used and commit, not >> used and max. >> >> On 3/24/13, nagarjuna kanamarlapudi <nagarjuna.kanamarlap...@gmail.com> >> wrote: >> > Hi, >> > >> > I configured my child jvm heap to 2 GB. So, I thought I could really >> read >> > 1.5GB of data and store it in memory (mapper/reducer). >> > >> > I wanted to confirm the same and wrote the following piece of code in >> > the >> > configure method of mapper. >> > >> > @Override >> > >> > public void configure(JobConf job) { >> > >> > System.out.println("FREE MEMORY -- " >> > >> > + Runtime.getRuntime().freeMemory()); >> > >> > System.out.println("MAX MEMORY ---" + >> > Runtime.getRuntime().maxMemory()); >> > >> > } >> > >> > >> > Surprisingly the output was >> > >> > >> > FREE MEMORY -- 341854864 = 320 MB >> > MAX MEMORY ---1908932608 = 1.9 GB >> > >> > >> > I am just wondering what processes are taking up that extra 1.6GB of >> > heap which I configured for the child jvm heap. >> > >> > >> > Appreciate in helping me understand the scenario. >> > >> > >> > >> > Regards >> > >> > Nagarjuna K >> > >> >> >> -- >> Ted. >> > -- Ted.